1. Technical Field
This invention relates to support systems, and more particularly, to systems such as mattresses, cushions, upholstery padding and the like having a resilient cellular material therein and to methods for manufacturing the same.
2. Description of the Prior Art
Many support systems exist within the art which attempt to provide pressure relief for an individual. A trade-off typically occurs in all such systems between comfort, stability and weight in order to achieve a marketable device. For example, support systems which contain liquid, such as waterbeds and water filled cushions, have various support benefits which are well known. On the other hand, such systems also exhibit many disadvantages. In particular, conventional waterbeds and water filled cushions produce a kind of wave action or rolling motion when in use due the tendency of water or other liquid inside the system to rush rapidly from one part thereof to another when an individual places his weight thereon, thereby forcing the liquid to flow to another part of the system. Moreover, since the envelope containing the liquid in such a system is typically elastically yieldable, a reaction to an initial liquid surge occurs. This reaction often results in a succession of countersurges within the envelope until the system reaches equilibrium. The described undamped surging and countersurging of the liquid in such systems is annoying to most users thereof. In order to obviate the above mentioned disadvantages, many waterbed manufacturers do not employ liquid displacement in that portion of the system which is intended to support the head and shoulders of the user. Instead, they employ a section of mattressing constructed in the conventional manner utilizing coil springs or other equivalent non-liquid structures. Obviously, this introduces an element of complexity to the manufacturing process and, as well, increased costs. Other manufacturers have attempted to dampen waterbed wave motion in various ways. In U.S. Pat. No. 3,585,356 the use of solid particles, such as Styrofoam.RTM., are disposed in liquid for this purpose. U.S. Pat. No. 3,736,604 uses flap means, as illustrated in FIG. 11 therein.
Saloff et al. describe in U.S. Pat. Nos. 4,942,634 and 4,370,768 (entitled "Damped Fluid Displacement Support System and Method for Making the Same" and "Damped Fluid Displacement Support System," respectively, both of which are assigned to the same assignee as the present invention) substantially completely stable damped liquid displacement support systems. In these systems, a core of resilient liquid absorbent material is disposed within a liquid impervious sealed envelope, the core being saturated with a liquid. When force is applied to the system the liquid within the cell migrates from one portion thereof to another before coming to equilibrium about the applied force. The foam core prevents the liquid from rushing from one region where pressure is applied to another region in the support cell. Thus, movement of the fluid within the cell is "damped" Further, the amount of water available to be displaced within the cell is less than one would find in a conventional system and, therefore, the damped liquid system weighs less than a conventional system.
Notwithstanding the commercial success of this damped system, certain drawbacks inherent in the liquid construction remain. For example, although lighter than preexisting liquid support systems, the jell or water used therein necessarily makes the weight of the system a consideration for many individuals who may wish to own such a device. Further, although better than conventional water support systems, a period of time is required before the damped liquid support system achieves equilibrium about an applied force, during which time there may be a feeling of instability in the individual using the system.
Non-liquid filled support systems, such as air filled mattress or cushion cells, are also typically unstable when pressure is applied thereto. In addition, such systems provide pressure relieving support characteristics generally inferior to those available with water filled systems.
Thus, there continues to exist a need for a new type of support system which achieves greater comfort and stability with less weight than presently available body support systems, while still providing comparable or superior pressure relieving support.